Research On XML Hardware Parser Based Vtd-xml Parsing Model

Extensible Markup Language (XML) is a widely used document data format standard, which is independent of any language and architecture. The data created by XML standard can be read by any application on any platform. So it is a platform-free data representing method. With these attributes, it has been widely used in electronic data exchange, Web data exchange, vector graphics, remote process calling and other fields.XML parsing is an important phase of dealing with XML documents or data streams. XML parsing refers to a method that extracts the XML document elements, attributes and content, and then use this information for further operations. For those applications that need to handle large amounts of data, this technique is particularly important. Selecting the appropriate analytical technique affects the performance of the application system greatly, as inappropriate parsing model will lead to excessive memory consumption and long processing time, which greatly affect the overall performance of the system. Because of the nature of XML data with redundancy inherent in some of its features, the processing of XML documents takes a large part of the cost in applications. XML software- based approach has become increasingly difficult to meet the need of application development. To find a suitable parsing model, the hardware circuit XML parser is a feasible direction to solve the problem.This paper analyzes the process of parsing XML documents, and makes a horizontal comparative analysis about the currently available XML parsing techniques and parsing model in terms of the streaming capabilities, access and modification capabilities and the hardware acceleration capability. By analyzing the working mechanism of VTD-XML parsing model, we make further improvement to the parser by making parallel processing and data compression. An XML parser with certain functions on a FPGA system has been impelemented, and all the hardware modules are developed by Verilog hardware description language. At the same time, an SOPC system has been build base on NIOS II soft-core technology to realize the node query capablilities for some specific XML documents after parsing, the simulation and test results show that the design met the design requirements well.